Abstract: The change of environment pressure will cause gas concentration errors detected by the UV-Fluorescence SO₂ detector. In order to improve the accuracy and reliability, the SO₂ concentration measurement in the range of 70–110 kPa was performed by NLPF-SO₂-01 analyzer and a pressure compensation model was established accordingly. The model includes zero-gas background compensation and indication compensation, which are applied to eliminate the influence of pressure on the baselines and indications, respectively. Through the compensation, the maximum relative error of the analyzer in the experiment is reduced from 7.37% to 0.65%. The experiments verify that the compensation model is valid, eliminating the impact of the pressure changes on concentration measurements and enhancing the accuracy of the measurements by the UV-Fluorescence SO₂ detector. It can be applied to the continuous monitoring of SO₂ at the desulfurization outlet or the main outlet of thermal power.